三轴加载条件下粗粒土剪切带的细观演化规律  

Meso-evolution of shear bands of coarse-grained soil under triaxial loading

作　　者：万航 周跃峰[2] 邓茂林[1] 左永振[2] 赵艺颖 王磊[2] WAN Hang;ZHOU Yuefeng;DENG Maolin;ZUO Yongzhen;ZHAO Yiying;WANG Lei(School of Civil Engineering and Architecture,China Three Gorges University,Yichang 430021,China;Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources,Changjiang River Scientific Research Institute,Wuhan 430010,China;China Institute of Water Resources and Hydropower Research,Beijing 100044,China)

机构地区：[1]三峡大学土木与建筑学院,湖北宜昌430021 [2]长江科学院水利部岩土力学与工程重点实验室,武汉430010 [3]中国水利水电科学研究院,北京100044

出　　处：《水力发电学报》2025年第1期54-63,共10页Journal of Hydroelectric Engineering

基　　金：国家自然科学基金资助项目(51979010,42172303);中央公益性科研院所基本科研业务费项目(CKSF2023318/YT)。

摘　　要：粗粒土被广泛应用于筑坝材料,宏观力学性质受其细观层面的颗粒运移和局部变形演化影响。通过对风化千枚岩进行CT三轴试验,并结合数字图像处理技术,量化分析粗粒土在控制速率加载下的颗粒运动和局部变形破坏过程,揭示其宏细观力学特性。结果表明:采用USM锐化以及材料分割对CT图像进行增强处理,有效凸显土颗粒的边界特征。试样内各区域的变形差异显著,靠近试样端部以较均匀的轴向压缩为主,破坏面附近局部变形表现为压缩和侧向扩移;剪切区域CT数平均值呈明显的先增后减规律,应变分布可由颗粒运动与局部变形反映。围压较大的试样剪切带发育为颗粒间的切向错动与法向扩移的耦合效应。试样沿着剪切面连续渐进发展,轴向应变16%左右各局部区域依次加速破坏。剪切带的形成经历了压密、孕育、扩展,直至贯通的渐进演化过程。Coarse-grained soil is widely used for the fill construction of rockfill dams and exhibits macroscopic mechanical properties affected by particle movement and mesoscopic deformation.In this study,Computed Tomography(CT)triaxial tests are conducted on coarse-grained soil of weathered phyllite,combined with digital image processing techniques,to quantitatively analyze its particle movement,local deformation and failure processes under controlled loading conditions(i.e.loading rates),focusing on the macro-and micro-structural characteristics.The results indicate that Unsharp Masking(USM)sharpening and material segmentation,when used to enhance CT images,will effectively highlight the boundary characteristics of soil particles.Significant deformation differences can be observed in various regions within a specimen.Near the two ends of the specimen,deformation takes a major form of relatively uniform axial compression,while near a failure surface,it manifests as compression and lateral spreading.In shear zones,the average CT number increases first and then decreases as an evident trend,indicating strain distribution is reflected by particle movement and local deformation.For a specimen with higher confine pressure,its shear bands show a coupling of tangential dislocation and normal dilation,developing progressively along the shear surface.At an axial strain around 16%,local regions accelerate to failure.Generally,shear band formation involves the stages of compaction,initiation,expansion,and penetration.

关 键 词：粗粒土 三轴试验 CT试验 图像处理 剪切带 破坏 

分 类 号：TU411[建筑科学—岩土工程]